Touch panels can be roughly classified into touch panels of resistive type, capacitive type, optical type, acoustic wave type, and electromagnetic type based on the sensing modes.
An optical type touch panel usually adopts the mechanism of blocking of light reception, in which light sources and receivers are arranged all over the panel in a matrix, and when light rays are blocked, the positions of the receivers receiving no signals can be recorded and thus the exact position of touch can be determined. Components of an optical type touch panel include a glass substrate, infrared light emitters and infrared light receivers. In a common configuration, infrared light emitters are disposed on the left and lower sides of a glass panel, and infrared receivers are disposed on the right and upper sides of the glass panel. When a finger or other contacting object blocks the infrared light, the position of the contact point in the matrix can be detected through signals received by the receivers.
However, an optical type touch panel generally requires both infrared light emitters and infrared receivers, and therefore has a complex structure and incurs a high cost.